Birdcage attachment



FIG. 1 is a front perspective of the new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines encircling the perches and post are portions of the article that form no part of the claimed design. The items shown in broken lines form no part of the claimed design. 

The ornamental design for a birdcage attachment, as shown and described. 